The present invention relates generally to monitors for use in measuring the concentration of glucose in a blood sample (said monitors being commonly referred to as blood glucose monitors in the art).
There are many medical conditions which require frequent measurement of the concentration of a particular analyte in the blood of a patient. For example, diabetes is a disease which typically requires a patient to routinely measure the concentration of glucose in his/her blood. Based upon the results of each blood glucose measurement, the patient may then require a particular drug treatment (e.g., an injection of insulin) in order to regulate that the blood glucose level of the patient remains within a specified range. Exceeding the upper limit of said range (hyperglycemia) or dropping beneath the lower limit of said range (hypoglycemia) should be avoided with as much diligence as possible to prevent the patient from experiencing serious medical complications which include, inter alia, retinopathy, nephropathy, and neuropathy.
A multi-step process is commonly practiced by diabetes patients to self-monitor the level of glucose present in their blood.
In the first step of said process, a patient is required to provide a blood sample suitable for testing. Blood samples taken from a patient for blood sugar monitoring are typically obtained by piercing the skin of the patient using a lancet device. A lancet device (also commonly referred to as a lancing device) typically includes a tubular body and a removable lancet. The body is typically adapted to be held by the user, the lancet being coupled to the body and being adapted to penetrate through the epidermis (the outermost layer of the skin) of the patient and into the dermis (the layer of skin directly beneath the epidermis) which is replete with capillary beds. The puncture of one or more capillaries by the lancet generates a sample of blood which exits through the incision in the patient's skin.
In some lancet devices, the lancet extends from the body at all times. In other lancet devices, the lancet is adapted to be moved, when actuated, from a retracted position in which the lancet tip is disposed within the body to an extended position in which the lancet tip extends beyond the body. Typically, the movement of the lancet from its retracted position to its extended position is effected with such force that contact of the moving lancet tip with the skin of a patient results in the piercing of the skin of the patient. In many such lancet devices having a movable lancet, the lancet is automatically drawn back into the body after reaching its extended position (e.g., using a spring) in order to minimize the risk of inadvertent lancet sticks.
Typically, the tubular body of a lancet device is designed for multiple uses. To the contrary, each individual lancet is individually wrapped and designed for a single use. In use, the individual lancet is removed from a sealed wrapping and mounted onto the lancet body. With the lancet mounted onto the body in this manner, the lancet device can be used to acquire a blood sample. After the blood sample has been acquired, the lancet is removed from the body and is discarded. Accordingly, this type of lancet is commonly referred to as a single-use disposable lancet in the art.
In the second step of said process, a blood glucose monitoring system is utilized to measure the concentration of glucose in the blood sample. One type of glucose monitoring system which is well known and widely used in the art includes a blood glucose meter (also commonly referred to a blood glucose monitor) and a plurality of individual, disposable, electrochemical test sensors which can be removably loaded into the meter. Examples of blood glucose monitoring systems of this type are manufactured and sold by Abbott Laboratories under the PRECISION line of blood glucose monitoring systems.
Each individual electrochemical test sensor typically includes a substrate which is formed as a thin, rectangular strip of non-conductive material, such as plastic. A plurality of carbon-layer electrodes are deposited (e.g., screen printed) on the substrate along a portion of its length in a spaced apart relationship, one electrode serving as the reference electrode for the test sensor and another electrode serving as the working electrode for the test sensor. All of the conductive electrodes terminate at one end to form a reaction area for the test sensor. In the reaction area (also commonly referred to as the reactive area), an enzyme is deposited on the working electrode. When exposed to the enzyme, glucose present in a blood sample undergoes a chemical reaction which produces a measurable electrical response. The other ends of the electrical contacts are disposed to electrically contact associated conductors located in the blood glucose monitor, as will be described further below.
A blood glucose monitor is typically modular and portable in construction to facilitate its frequent handling by the patient. A blood glucose monitor often comprises a multi-function test port which is adapted to receive the test sensor in such a manner so that an electrical communication path is established therebetween. As such, an electrical reaction created by depositing a blood sample onto the reaction area of the test sensor travels along the working electrode of the test sensor and into the test port of the blood glucose monitor. Within the housing of the monitor, the test port is electrically connected to a microprocessor which controls the basic operations of the monitor. The microprocessor, in turn, is electrically connected to a memory device which is capable of storing a multiplicity of blood glucose test results.
In use, the blood glucose monitoring system of the type described above can be used in the following manner to measure the glucose level of a blood sample and, in turn, store the result of said measurement into memory as test data. Specifically, a disposable test sensor is unwrapped from its packaging and is inserted into the test port of the monitor. With the test sensor properly inserted into the monitor, there is established a direct electrical contact between the conductors on the test sensor and the conductors contained within the test port, thereby establishing an electrical communication path between the test sensor and the monitor. Having properly disposed the test sensor into the test port, the monitor typically displays a “ready” indication on its display.
The user is then required to provide a blood sample using a lancet device. Specifically, as noted above, a disposable lancet is unwrapped from its protective packaging and is loaded into a corresponding lancet device. The lancet device is then fired into the skin of the patient to provide a blood sample.
After lancing the skin, the patient is required to deposit one or more drops of blood from the patient's wound site onto the reaction area of the test sensor. When a sufficient quantity of blood is deposited on the reaction area of the test sensor, an electrochemical reaction occurs between glucose in the blood sample and the enzyme deposited on the working electrode which, in turn, produces an electrical current which decays exponentially over time. The decaying electrical current created through the chemical reaction between the enzyme and the glucose molecules in the blood sample, in turn, travels along the electrically conductive path established between the test sensor and the monitor and is measured by the microprocessor of the monitor. The microprocessor of the monitor, in turn, correlates the declining current to a standard numerical glucose value (e.g., using a scaling factor). The numerical glucose value calculated by the monitor is then shown on the monitor display for the patient to observe. In addition, the data associated with the particular blood glucose measurement is stored into the memory for the monitor.
As can be appreciated, the aforementioned method for conducting a blood glucose test necessitates the possession of a large quantity of separate components. Specifically, in order to perform a single blood glucose test using the method described above, a user is required to possess, inter alia, a reusable lancet base, a disposable lancet, a modular blood glucose monitor and a disposable test strip.
Diabetes patients often find it difficult to hold such a large quantity of individual test components. In fact, it has been found that patients often lose or misplace one or more the aforementioned components. As a result, the patient is often precluded from performing routine blood glucose tests which, in turn, can seriously jeopardize the health of the patient.
Accordingly, blood glucose monitoring kits are well known in the art. Blood glucose monitoring kits provide a patient with means for easily storing all of the components which are required to perform a test. Specifically, a blood glucose monitoring kit commonly includes an enclosable case into which all of the aforementioned components can be removably stored. As such, when a test is required, the user simply opens the case and removes the necessary components therefrom in order to perform an assay. Upon completion of the test, the reusable components are returned to the pouch and the disposable components are discarded. The pouch is then closed until such time that further testing is required.
Although useful in simplifying the handling of a large quantity of individual components, kits of the type described above suffer from a couple notable disadvantages.
As a first disadvantage, it has been found that kits of the type described above are somewhat bulky in size. In particular, the relatively large size of conventional blood glucose monitors tends to significantly increase the overall size (and, in particular, the thickness) of the kit. As a result, the patient often finds it to be considerably uncomfortable to store the kit on his/her person (e.g., in a clothing pocket) between tests, which is highly undesirable.
As a second disadvantage, the fact that all of the blood glucose testing components are removably stored within the case increases the number of preparatory steps that a patient must undertake prior to performing an assay. Specifically, the user must first open the case (e.g., by unzipping, unsnapping, etc.) in order to access the various components contained therein. With the case open, the user must then remove the lancet base and blood glucose monitor therefrom. Preferably, the monitor is then positioned on a flat and stable surface to facilitate its use. Next, the patient must remove a disposable lancet and a disposable test strip from the pouch. In turn, the disposable lancet and the disposable test strip must be unwrapped and installed into their corresponding tools. Only after completion of all these preparatory steps can the user perform an assay, which is highly undesirable.